Evaporator and entrainment separator

ABSTRACT

An evaporator and entrainment separator for evaporating water from a toxic solution and releasing water vapor to the atmosphere includes a tank for containing the toxic solution, one or more vertical stacks mounted over the tank and containing a plurality of moisture entrainment grids and a spray nozzle which directs heated solution from the tank down onto one of the entrainment grids. A blower draws air across the surface of the heated solution in the tank and up through the stacks.

United States Patent [1 1 Zievers et al.

[451 Sept. 25, 1973 1 1 EVAPORATOR AND ENTRAINMENT SEPARATOR [75]Inventors: James F. Zievers; Clay W. Riley,

both of La Grange, I11.

[73] Assignee: Industrial Filter & Pump Mfg. Co.,

Cicero, Ill.

[22] Filed: Mar. 24, 1971 [21] Appl. No.: 127,470

[51] Int. Cl B0ld 47/02 [58] Field of Search 55/233, 228, 250, 55/485,489, 528, 499, 239, 223, 259, 510,

[56] References Cited UNITED STATES PATENTS 2,239,595 4/1941 Cummings,Jr. 261/141 X 2,897,146 7/1959 Waddill 203/40 X FOREIGN PATENTS ORAPPLICATIONS 447,215 3/1948 Canada 55/489 X Primary ExaminerTim R. MilesAssistant ExaminerWilliam Cuchlinski, Jr. Attorney-Fidler, Patnaude &Batz [5 7] ABSTRACT An evaporator and entrainment separator forevaporating water from a toxic solution and releasing water vapor to theatmosphere includes a tank for containing the toxic solution, one ormore vertical stacks mounted over the tank and containing a plurality ofmoisture entrainment grids and a spray nozzle which directs heatedsolution from the tank down onto one of the entrainment grids. A blowerdraws air across the surface of the heated solution in the tank and upthrough the stacks.

7 Claims, 4 Drawing Figures Kr" jaws 32 a] 29 30 l/l959 Great Britain55/223 X PATENTEI] SEPZ 5 I975 sumum ATTORNEYS PMENIEDSEPZSWH SHEET 2 0F2 INVENTORS JAMES F. ZIEVERS BY CLAY W RILEY -\:r%

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ATTORNEYS EVAPORATOR AND ENTRAINMENT SEPARATOR The present inventionrelates to a method and apparatus for evaporating water from a toxicsolution and releasing it to the atmosphere in the form of non-toxicwater vapor.

The disposal of toxic solutions and the recovery of various constituentsthereof, such, for example, as metal ions, is becoming of ever greaterimportance because or stricter pollution control laws and regulationsand because of the increased value of the recoverable materials.Depending upon the economics of a particular situation, variousdifferent systems, both chemical and mechanical, are available forreducing the toxicity of the solutions and recovering parts thereof.Many such systems require evaporation of water from the solutions, andevaporators have been manufactured for this purpose. Inasmuch as thesolution undergoing evaporation is frequently toxic or otherwiseobjectionable, it is important to prevent its release to the atmosphere.Apparatus has also been manufactured for preventing the emission ofdroplets of such solutions along with the water vapor. Such evaporatorsand separators have been expensive tomanufacture and operate; have, forthe most part, been custom designed and manufactured for eachinstallation; and have not performed satisfactorily in many instances.Moreover, where a processing system has been enlarged, the evaporatorand- /or the separator had to be replaced with larger units.

Therefore, an object of the present invention is to provide a new andimproved evaporator and entrainment separator.

Another object of the present invention is to provide a new and improvedevaporator and entrainment separator which can be readily increased inoperating capacity.

A further object of the present invention is to provide a new andimproved method for evaporating water from an aqueous solution.

A still further object of the present invention is to provide a new andimproved entrainment separator.

Briefly, the above and further objects may be realized in accordancewith the present invention by providing a tank and one or moreentrainment separator modules mounted thereon. Air is drawnacross thesurface of the solution in the tank and discharged through theseparators to the atmosphere. The separator modules each includes a pairof entrainment grids spaced apart one above the other and a spray nozzlefor directing a spray of the heated solution downwardly into the spacebetween grids where it is vaporized by the up-flowing air. The grids arehydrophobic whereby moisture droplets entrained thereby fall by gravityinto the tank and are heated and recirculated to the spray nozzles. Thecapacity of the system can be increased by simply increasing the size ofthe blower and the number of entrainment stacks.

Further objects and advantages and a better understanding of theinvention may be had from the following detailed description taken inconnection with the accompanying drawings, wherein:

FIG. 1 is a perspective view of an evaporator and entrainment separatorembodying the present invention;

FIG. 2 is a partially sectioned view of a spray nozzle embodying anotheraspect of the present invention;

FIG. 3 is a perspective view of an entrainment grid unit embodying thepresent invention and partially broken away to show the internalconstruction thereof; and

FIG. 4 is an enlarged, fragmentary view of a portion of the grid unit ofFIG. 3.

Referring now to the drawings, and particularly to FIG. 1 thereof, thereis shown an evaporator and entrainment separator generally indicated atand comprising as its principal parts a tank 11; a pump 12; a heatexchanger 13; a plurality of entrainment separator modules 14 and 15each containing a pair of entrainment grid units 16 and 17 and adistributor spray nozzle 18; an air inlet hood 20; and a blower, notshown, for blowing air from an outlet duct 21. Briefly considered, thesolution to be evaporated is pumped by the pump 12 through the heatexchanger 13 wherein its temperature is elevated to about 140 F. andthen to the distributor nozzles 18 which atomizes the solution andsprays it downwardly toward the entrainment grids 17. At this same time,the blower is drawing fresh air in through the inlet duct 20 from whichit passes across the surface of the solution contained in the tank 1 1and up through the entrainment stacks 14 and 15 and out through theoutlet 21. Preferably, the inlet 20 and the outlet 21 are connected bysuitable air ducts to the exterior of the building in which the unit 10'is located. It will thus be seen thatthe air, and liquid particlesentrained thereby, pass upwardly through the entrainment stacks l4 and15 while the vapor spray from the nozzles 18 is directed downwardly inthe opposite direction.

As is explained in greater detail hereinafter, the entrainment grids l6and 17 are preferably identical in construction and present a tortuouspath to the air and vapor passing therethrough. The grids are formed ofa hydrophobic material so that any moisture droplets which condensethereon fall by gravity back into the tank 11. It will be noted that theupper entrainment grid 17 is mounted at an angle of approximately 20 sothat the liquid captured thereby flows to one edge of the grid unitwhere it collects into relatively large drops which fall along one sideof the stack onto the lower grid and then through the lower grid intothe tank. When the level of liquid in the tank has reached an optimumlevel of approximately 6 inches below the top of the tank, the outletfrom the tank is connected by suitable valving to the inlet of the pump12 whereby the liquid solution in the tank 11 is continuouslyrecirculated through the heat exchanger and the distributor nozzles 18.An amount of liquid equal to the amount being evaporated by the unit 10may then be continuously fed to the pump 12 in addition to the solutionbeing recirculated from the tank 11 thereby maintaining a constant levelof liquid in the tank 11.

Considering the unit 10 in greater detail, the tank 11 is rectangular incross section and supported on a plurality of legs 23. A pipe 24connects to the bottom of the tank 11 at the forward end thereof asshown in flG. 1 and to a T-connector 25 having one leg thereof connectedthrough a manual valve 26 to a T-connector 27 which is in turn connectedto the inlet of the pump 12. The other leg of the T-connector 27 isconnected through a valve 28 to a T-connector 29 having one leg thereofconnected to an inlet line 30. The other leg of the T-connector 29 isconnected through a valve 31 and a relatively small line 32 to the otherleg of the T- connector 25. The line 32 including the valve 31 thusprovides a bypass to the tank 11 around the valves 26 and 28. This lineis used to supply liquid to the tank 1 1 under normal operatingconditions to replace the evaporated liquid and maintain the liquidlevel in the tank 11 constant.

The outlet of the pump 12 is connected to a line 34 which is in turnconnected through a valve 35 to an inlet 36 to the heat exchanger 13.The outlet 37 from the heat exchanger 13 is connected through a verticalline 39, a line 40 and a horizontal manifold 41 extending along the backof the unit directly behind the lower ends of the stack modules 14 and15. The manifold 41 is connected through suitable valves 42 to each ofthe distributor spraynozzles 18. The heat exchanger 13 is conventionalin that the liquid inlet and outlet lines 36 and 37 connect to oppositeends of a spiral tube extending the length of the heat exchanger. Theheating medium such, for example, as steam, is supplied to an inlet 44through a control valve 45 which is responsive to the temperature of theliquid in a control device 47 connected to the line 39 so as to admit asufficient amount of steam to the heat exchanger 13 to maintainthetemperature of the liquid being sprayed from the nozzles 18 at thedesired value. The steam outlet from the heat exchanger 13 is not shownbut is conventional and includes a steam trap to prevent live steam frombeing exhausted into the atmosphere in the vicinity of the unit 10.

The entrainment separator stacks 14 and are identical and aremanufactured as modular units so as to be usable with different sizes ofevaporators. For example, in a smaller unit than that shown in FIG. 1,the tank would be substantially shorter and only a single stack would beused. On the other hand, where a relatively small capacity unit isneeded at first but it is anticipated that a larger evaporator will berequired in the future then a tank such as tank 1 1 is employed usingonly the stack 14, in which case a cover plate is placed over theportion of the tank 11 shown occupied by the stack 15 in FIG. 1. Then,at a later date, the additional stack can be added.

As shown in FIG. 1, the entrainment separator stack modules are eachprovided with a pair of rectangular enlargements 50 and 51 in which theentrainment grids 16 and 17 are located. As is explained in greaterdetail hereinafter in connection with FIGS. 3 and 4, the entrainmentgrid units 16 and 17 have a peripheral imperforate portion. Theenlargements provide spaces for receiving these peripheral portions sothat the full area of the stacks are employed and are not decreased bythe entrainment grid units 16 and 17. The forward faces of theenlargements 50 and 51 are removable panels so as to permit access tothe entrainment grids and also to the distributor spray nozzles 18.

Mounted above the stack modules 14 and 15 is a hood 52 which couples theefiluent from the entrainment modules 14 and 15 to the blower locatedwithin the housing 53 located between the hood 52 and the exhaust port21. An electric motor 54 is drivingly connected to the blower and isenergized whenever the system is in operation. An advantage achieved byplacing the blower near the exhaust and of the unit 10 is that any leaksin the system do not permit the release of noxious gases or vapor to thearea surrounding the unit 10.

. Referring now to FIG. 2, there is shown a distributor spray nozzle 18.The nozzle 18 as shown in FIG. 1 extends substantially across the widthof the stack modules in which it is mounted and comprises a rigid tube55 provided with a plug 56 at the distal end and an apertured mountingflange 57 at the other end. The tube 55 is provided with a plurality ofpairs of slots 58 which may conveniently be cut into the tube 55 by asaw blade. These cuts, which diverge toward the axis of the tube areangled at about degrees relative to the axis of the tube and the cuts ineach pair are spaced apart by about 1% inches and the pairs are spacedabout 2% inches apart. The nozzle 18, is therefore, easily andinexpensively constructed and provides a very effective liquid spraythroughout substantially the entire crosssectional area of the lowerentrainment grid 17.

Referring to FIG. 3, there is shown one of the entrainment grid units16. It includes a pleated grid member 60 sandwiched between a pair ofsimilar pleated grid members 61 and 62 with the pleats of the gridmembers 61 and 62 extending perpendicular to the pleats of the gridmember 60. The grid members 60-62 are formed of a perforate materialwhich, as best shown in FIG. 5, comprises a plurality of parallelfilaments 63a and a plurality of cross filaments 63b bonded together attheir points of intersection but not woven together. The filaments 63aand 63b are formed of polyethylene or some other hydrophobic shaperetaining material which is sufficiently flexible when heated so as tobe formable into the tight pleats required in the entrainment grid units16 and 17. In a successful reduction to practice of the presentinvention, approximately five pleats per inch were employed with thethickness of each of the pleated units 60 -62 being 1% inches.Accordingly, the entrainment grids were approximately 3% inches thick.

Each entrainment grid unit 16 and 17 thus includes three of the pleatedgrid units 60-62 sandwiched together as shown in FIG. 3. Each of theopen edges of the pleats in the center grid 60 is closed off by animperforate strip 62 which overlies the open edges of these pleats andextends into the end pleats of the upper and lower grids 61 and 62. Theopen edges of the pleats in the grids 61 and 62 are closed off byimperforate strips 65 and 66. The strip 66 overlies the open end of thepleats in the grid 62 and extends into the end pleat of the center grid60. The strip 65 overlies the open end of the pleats in the grid 61 andextends into the next to last pleat in the center grid 60.

The stack of grids 60-62 are supported in a square frame which includesa pair of top and bottom frame members 68 and 69, four imperforate,right-angle corner members 70, and four imperforate side wall members71. The comer members 70 and the wall members 71 are cemented to theframe members 68 and 69 to form an integral unit. Flanges 74 on theframe members 68 and 69 hold the grid stack 60-62 within the frame.

The system as shown in FIG. 1 utilizes a heat exchanger located outsideof the tank 11. If desired, the heat exchanger may be located inside ofthe tank 11, but it is preferred that the solution be passed through theheat exchanger immediately prior to being supplied to the distributorspray nozzles 18 so that the temperature of the sprayed solution ishigher than the average temperature of the solution in the tank 11. Atthe higher temperature and being in the form of a fine spray, it morereadily evaporates within the stacks 14 and 15 and provides a moreefficiently operating system.

While the present invention has been described in connection withparticular embodiments thereof, it will be understood that many changesand modifications of this invention may be made by those skilled in theart without departing from the true spirit and the scope thereof.Accordingly, the appended claims are intended to cover all such changesand modifications as fall within the true spirit and scope of thepresent invention.

What is claimed is:

1. An evaporator and entrainment separator for vaporizing a solution,comprising an elongated tank for containing said solution,

said tank having a rectangular open top,

heat exchanger means mounted adjacent said tank and connected theretofor heating said solution,

a plurality of entrainment separator assemblies mounted in side-by-siderelationship on said tank over said open top,

each of said separator assemblies including a vertical duct having aplurality of entrainment grid units mounted therein one above the otherin spaced apart relationship and an atomizer mounted between said gridunits for spraying the heated solution toward the lower one of saidgridunits, and

a blower mounted on and above said tank in line with said ducts andconnected to the tops of said ducts for drawing air into said tankthrough the portion of said open top below said blower, across thesurface of the solution in said tank and upwardly through saidentrainment separator assemblies.

2. An evaporator and entrainment separator according to claim 1 whereinsaid grid units are formed of a hydrophobic plastic material.

3. An evaporator and entrainment separator according to claim 2 whereinsaid grid units are identical.

4. An evaporator and entrainment separator according to claim 2 whereineach of said grid units comprises a plurality of pleated, perforate,plastic members lying in face-to-face relationship with the pleats inadjacent members extending in mutually orthogonal directions.

5. An evaporator and entrainment separator according to claim 1 whereinsaid heat exchanger is mounted externally of said tank, and furthercomprising means circulating the solution from said tank, through saidheat exchanger and to said atomizer.

6. An evaporator and entrainment separator comprising a tank forcontaining said solution,

a heat exchanger for heating said solution,

an entrainment separator assembly mounted over an opening in the upperportion of said tank,

said separator assembly including a duct and a plurality of verticallyspaced apart entrainment grid units mounted in said duct,

means for forcing air across the surface of the solution in said tankand upwardly through said separator assembly, and

an atomizer mounted between said grid units for spraying the heatedsolution toward the lower one of said grid units,

said grid units each comprising a plurality of pleated, perforate,hydrophobic plastic members lying in face-to-face relationship with thepleats in adjacent members extending in mutually orthogonal directions,and

strip means overlying and blocking the open edges of the pleats in saidplastic members.

7. An entrainment separator grid comprising a plurality of pleated,perforate, hydrophobic plastic members lying in face-to-facerelationship with the pleats in adjacent members extending in mutuallyorthogonal directions,

a plurality of imperforate strips overlying the open edges of the pleatsin said plastic members,

said strips extending into the pleats of the adjacent plastic members,and

a unitary frame encircling said plastic members and said strips andholding said grid in assembled relationship,

1. An evaporator and entrainment separator for vaporizing a solution,comprising an elongated tank for containing said solution, said tankhaving a rectangular open top, heat exchanger means mounted adjacentsaid tank and connected thereto for heating said solution, a pluralityof entrainment separator assemblies mounted in sideby-side relationshipon said tank over said open top, each of said separator asSembliesincluding a vertical duct having a plurality of entrainment grid unitsmounted therein one above the other in spaced apart relationship and anatomizer mounted between said grid units for spraying the heatedsolution toward the lower one of said grid units, and a blower mountedon and above said tank in line with said ducts and connected to the topsof said ducts for drawing air into said tank through the portion of saidopen top below said blower, across the surface of the solution in saidtank and upwardly through said entrainment separator assemblies.
 2. Anevaporator and entrainment separator according to claim 1 wherein saidgrid units are formed of a hydrophobic plastic material.
 3. Anevaporator and entrainment separator according to claim 2 wherein saidgrid units are identical.
 4. An evaporator and entrainment separatoraccording to claim 2 wherein each of said grid units comprises aplurality of pleated, perforate, plastic members lying in face-to-facerelationship with the pleats in adjacent members extending in mutuallyorthogonal directions.
 5. An evaporator and entrainment separatoraccording to claim 1 wherein said heat exchanger is mounted externallyof said tank, and further comprising means circulating the solution fromsaid tank, through said heat exchanger and to said atomizer.
 6. Anevaporator and entrainment separator comprising a tank for containingsaid solution, a heat exchanger for heating said solution, anentrainment separator assembly mounted over an opening in the upperportion of said tank, said separator assembly including a duct and aplurality of vertically spaced apart entrainment grid units mounted insaid duct, means for forcing air across the surface of the solution insaid tank and upwardly through said separator assembly, and an atomizermounted between said grid units for spraying the heated solution towardthe lower one of said grid units, said grid units each comprising aplurality of pleated, perforate, hydrophobic plastic members lying inface-to-face relationship with the pleats in adjacent members extendingin mutually orthogonal directions, and strip means overlying andblocking the open edges of the pleats in said plastic members.
 7. Anentrainment separator grid comprising a plurality of pleated, perforate,hydrophobic plastic members lying in face-to-face relationship with thepleats in adjacent members extending in mutually orthogonal directions,a plurality of imperforate strips overlying the open edges of the pleatsin said plastic members, said strips extending into the pleats of theadjacent plastic members, and a unitary frame encircling said plasticmembers and said strips and holding said grid in assembled relationship.